1971: After years as a romantic balladeer, Marvin Gaye
releases his pivotal album, "What's Going On." The Motown
soul set finds the singer/songwriter waxing eloquently
about political and environmental issues, as well as the
Vietnam War and drug addiction, in such songs as "Mercy
Mercy Me," "Inner City Blues (Make Me Wanna Holler)" and
the title track.

1971: Led Zeppelin releases its eponymous (and
ultimately best-selling) fourth album. The Atlantic set
marked by the epic power ballad "Stairway to Heaven,"
arugably the most popular track in the history of rock
radio, despite the fact that it was never released as
a commercial single.

1972: Stevie Wonder's "Music of My Mind" is his first
issued under a new-and then unprecedented-contract with
Motown. The introspective set is a unified document on
which Wonder plays nearly every instrument. The album
presages a highly creative period that delivers "Talking
Book" the same year, followed by "Innervisions (1973),
"Fulfillingness' First Finale" (1974) and "Songs in the
Key of Life" (1976).

1972: Bob Marley releases "Catch a Fire," his first
album for Chris Blackwell's Island Records. Despite subsequent
landmarks as 1973's "Burnin'" and 1974's "Natty Dread,"
the reggae icon doesn't explode in the U.S. until 1976,
when "Rastaman Vibration" reaches No. 8 on Billboard's
Top LPs chart.

1973: Pink Floyd releases "The Dark Side of the
Moon" (Harvest/Capitol). The U.K. progressive rock act's
breakthrough reaches No. 1 on Billboard's albums chart
and goes on to set a record by remaining on the list for
741 weeks.

The feat is virtually unattainable under the chart's rules
as they stand in 2004, where albums that fall below No.
100 and are two years old or more are removed from The
Billboard 200 and placed on the Top Pop Catalog chart.

As of the Nov. 13, 2004, issue of Billboard, "Dark Side
of the Moon" had accumulated 1,242 chart weeks, combining
its time on main chart and the Top Pop Catalog lists.

1975: The Who's film "Tommy" is released, starring lead
singer Roger Daltrey as the title character. Directed
by Ken Russell, the landmark rock opera also features
the rest of the band as well as musicians Elton John,
Eric Clapton, Tina Turner and Arthur Brown, and actors
Ann Margret and Jack Nicholson, among others. It marks
the band's debut in film, a medium it would revisit twice
in 1979 with the release of the documentary "The Kids
Are Alright" and another rock opera, "Quadrophenia."

1975: Two months after the August release of his
breakthrough album "Born to Run" (Columbia), Bruce Springsteen
simultaneously appears on the covers of Time and Newsweek
magazines. The set reaches No. 3 on Billboard's Top LPs
chart. more
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1975: Donna Summer scores her first hit with "Love
to Love You Baby" (Oasis), which peaks at No. 2 on Billboard's
Hot 100. Dubbed the Queen of Disco, the multi-Grammy-winning
artist would go on to net 13 additional top 10 singles,
four of which reached the pole position. Additionally,
three of her albums, including "Bad Girls," peaked at
No. 1 on the Billboard albums chart.

1975: The Eagles release their fourth album, "One
of These Nights" (Asylum), which becomes the band's first
Billboard No. 1. The set features the singles "Lyin' Eyes"
and the title track, which reach No. 2 and No. 1, respectively,
on Billboard's Hot 100.

"One of These Nights" is the first of five No. 1 albums from
the quintessential 1970s California-based rock band. The
year 1976 brought two -- "Hotel California" and "Their
Greatest Hits 1971-1975" -- and in 1979 "The Long Run"
reached the summit. It would be another 15 years before
the band hit the top of the Billboard album tally again
with the reunion album 1994 "Hell Freezes Over" (Geffen).

At deadline, "Their Greatest Hits 1971-1975" (Asylum)
is considered the best-selling album of all time, certified
by the Recording Industry Association of America for U.S.
shipments of 28 million copies. (The album's status occasionally
slips behind Michael Jackson's "Thriller," which at deadline
is certified for 26 million).

1975: Columbia Pictures-owned Bell Records is rechristened
Arista Records by Clive Davis, who names the label after
his secondary school honor society. The label's early
success with Barry Manilow, Melissa Manchester and the
Bay City Rollers sets the stage for future blockbusters
from Dionne Warwick, Air Supply and Whitney Houston.

1976: The Copyright Act of 1976 becomes the exclusive
source of legal protection for qualified creative works
"fixed in a tangible medium," whether published or unpublished.
For works created after its effective date of 1978, other
than "works for hire," it extends protection for the life
of the author plus 50 years (now 70 years).

1976: The Ramones' self-titled debut is released
by Sire Records, garnering critical acclaim but almost
no radio play and peaks at just No. 111 on Billboard's
Top Albums chart. Yet it serves as a blueprint for punk
-- simple, anthemic songs played fast -- and inspires
a generation of rock musicians. The Ramones had 15 charting
albums, of which only four crashed the top 100 and none
went higher than No. 44. Yet their spirit and influence
was undeniable; they were inducted into the Rock and Roll
Hall of Fame in 2004.

1976: "Wanted: The Outlaws" marks the breakthrough
of country music's outlaw movement. The album featured
Jessi Colter, Waylon Jennings, Willie Nelson and Tompall
Glaser and remained at No. 1 for six weeks on Billboard's
Top Country Albums chart. In November 1976, it became
the first country album to be certified platinum by the
RIAA.

1977: The "Saturday Night Fever"
soundtrack (RSO) spends 24 weeks at No. 1 on the Billboard
albums chart. The film (starring John Travolta) and soundtrack
(with music composed by the Bee Gees) introduced disco
music to the mainstream. At the 21st annual Grammys, the
two-disc soundtrack wins the album of the year award.

1977: The year punk broke.
Although the Sex Pistols' lone studio album, "Never Mind
the Bollocks..." reached only No. 110 on Billboard's Top
LPs chart, it sparked a worldwide musical revolution driven
by the Clash, the Buzzcocks and the Ramones.

1979: Sony and Philips invent the compact disc,
which would be introduced to the public in 1982. That
same year, Sony introduces the Soundabout, the forerunner
of the wildly popular portable cassette player the Walkman.

1979: The Sugarhill Gang scores rap's first mainstream
hit on Billboard's Hot 100 with "Rapper's Delight," which
reaches No. 36. The song's infectious appeal is owed in
part to its rhythmic sampling of Chic's "Good Times."